Replace the coolant temperature sensor (ECT sensor) on the 2.5L I4 engine to restore accurate coolant temperature readings to the ECM and instrument cluster.

Warnings

Tools required

Parts

• Engine coolant temperature sensor × 1 — Use OEM specification
• Coolant temperature sensor o-ring or gasket × 1 — Often included with sensor

Fluids

• Toyota Super Long Life Coolant (Pink) — 1.5 qt

Preparation

1. Ensure engine is completely cold to the touch (wait at least 2 hours after last operation)
2. Park vehicle on level ground and engage parking brake
3. Remove engine cover by pulling upward on the front edge, then lifting off
4. Locate the coolant temperature sensor on the thermostat housing at the front-right side of the engine block
5. Place drain pan beneath the thermostat housing area to catch coolant spillage

Procedure

1. 1

   Disconnect electrical connector
   Press the locking tab on the coolant temperature sensor electrical connector and pull straight out to disconnect. Do not pull on the wiring harness itself.
2. 2

   Remove coolant temperature sensor
   Using a 19mm deep socket with extension, turn the sensor counterclockwise to remove. Be prepared for approximately 1-2 cups of coolant to drain from the opening. Keep drain pan positioned to catch all fluid. Remove the sensor completely and allow coolant to drain into the pan.
3. 3

   Inspect thermostat housing bore
   Wipe the sensor mounting bore clean with a shop towel. Inspect the threads in the thermostat housing for any damage or corrosion. Check that the old o-ring or gasket has been removed completely and is not stuck in the housing.
4. 4

   Prepare new sensor
   Remove the new coolant temperature sensor from packaging. Verify that a new o-ring or gasket is installed on the sensor threads. If the o-ring is separate, install it onto the sensor now. Lightly coat the o-ring with fresh coolant to aid installation.
5. 5

   Install new sensor
   Thread the new coolant temperature sensor into the thermostat housing by hand, turning clockwise. Thread it in as far as possible by hand to ensure proper thread engagement. Then use the 19mm socket to tighten to 15 Nm (11 lb-ft). Do not overtighten as this can damage the plastic housing or strip the threads.
   Torque spec

   Housing Bolts14 Nm (10 lb-ft)
6. 6

   Reconnect electrical connector
   Push the electrical connector onto the new sensor until you hear and feel a positive click. Tug gently on the connector to verify it is locked in place.
7. 7

   Refill coolant and bleed system
   Add Toyota Super Long Life Coolant (Pink) to the radiator and overflow reservoir to restore the proper level. Start the engine and allow it to reach operating temperature with the heater on maximum. Monitor coolant level and add as needed. Squeeze the upper radiator hose several times to help purge air from the system. Top off coolant to the FULL mark on the overflow reservoir when engine is fully warmed up.

Reassembly

1. Reinstall engine cover by positioning it over the mounting grommets and pressing down firmly until it clicks into place
2. Wipe down any spilled coolant from engine components and surrounding areas

Verification

• Start engine and verify no coolant leaks from the sensor location
• Allow engine to reach operating temperature and confirm temperature gauge reads normally (middle of range)
• Using an OBD-II scanner, verify ECT sensor readings match actual coolant temperature (should read 180-195°F at full operating temperature)
• Check coolant level in overflow reservoir after engine cools and top off if necessary
• Verify no diagnostic trouble codes are present related to coolant temperature sensor

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